1 /*
2 * Copyright (c) 1993, 1994, 1995, 1996, 1997
3 * The Regents of the University of California. All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that: (1) source code distributions
7 * retain the above copyright notice and this paragraph in its entirety, (2)
8 * distributions including binary code include the above copyright notice and
9 * this paragraph in its entirety in the documentation or other materials
10 * provided with the distribution, and (3) all advertising materials mentioning
11 * features or use of this software display the following acknowledgement:
12 * ``This product includes software developed by the University of California,
13 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
14 * the University nor the names of its contributors may be used to endorse
15 * or promote products derived from this software without specific prior
16 * written permission.
17 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
18 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
19 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
20 *
21 * sf-pcap.c - libpcap-file-format-specific code from savefile.c
22 * Extraction/creation by Jeffrey Mogul, DECWRL
23 * Modified by Steve McCanne, LBL.
24 *
25 * Used to save the received packet headers, after filtering, to
26 * a file, and then read them later.
27 * The first record in the file contains saved values for the machine
28 * dependent values so we can print the dump file on any architecture.
29 */
30
31 #ifdef HAVE_CONFIG_H
32 #include <config.h>
33 #endif
34
35 #include <pcap-types.h>
36 #ifdef _WIN32
37 #include <io.h>
38 #include <fcntl.h>
39 #endif /* _WIN32 */
40
41 #include <errno.h>
42 #include <memory.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46
47 #include "pcap-int.h"
48
49 #include "pcap-common.h"
50
51 #ifdef HAVE_OS_PROTO_H
52 #include "os-proto.h"
53 #endif
54
55 #include "sf-pcap.h"
56
57 /*
58 * Setting O_BINARY on DOS/Windows is a bit tricky
59 */
60 #if defined(_WIN32)
61 #define SET_BINMODE(f) _setmode(_fileno(f), _O_BINARY)
62 #elif defined(MSDOS)
63 #if defined(__HIGHC__)
64 #define SET_BINMODE(f) setmode(f, O_BINARY)
65 #else
66 #define SET_BINMODE(f) setmode(fileno(f), O_BINARY)
67 #endif
68 #endif
69
70 /*
71 * Standard libpcap format.
72 */
73 #define TCPDUMP_MAGIC 0xa1b2c3d4
74
75 /*
76 * Alexey Kuznetzov's modified libpcap format.
77 */
78 #define KUZNETZOV_TCPDUMP_MAGIC 0xa1b2cd34
79
80 /*
81 * Reserved for Francisco Mesquita <francisco.mesquita@radiomovel.pt>
82 * for another modified format.
83 */
84 #define FMESQUITA_TCPDUMP_MAGIC 0xa1b234cd
85
86 /*
87 * Navtel Communcations' format, with nanosecond timestamps,
88 * as per a request from Dumas Hwang <dumas.hwang@navtelcom.com>.
89 */
90 #define NAVTEL_TCPDUMP_MAGIC 0xa12b3c4d
91
92 /*
93 * Normal libpcap format, except for seconds/nanoseconds timestamps,
94 * as per a request by Ulf Lamping <ulf.lamping@web.de>
95 */
96 #define NSEC_TCPDUMP_MAGIC 0xa1b23c4d
97
98 /*
99 * Mechanism for storing information about a capture in the upper
100 * 6 bits of a linktype value in a capture file.
101 *
102 * LT_LINKTYPE_EXT(x) extracts the additional information.
103 *
104 * The rest of the bits are for a value describing the link-layer
105 * value. LT_LINKTYPE(x) extracts that value.
106 */
107 #define LT_LINKTYPE(x) ((x) & 0x03FFFFFF)
108 #define LT_LINKTYPE_EXT(x) ((x) & 0xFC000000)
109
110 static int pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **datap);
111
112 /*
113 * Private data for reading pcap savefiles.
114 */
115 typedef enum {
116 NOT_SWAPPED,
117 SWAPPED,
118 MAYBE_SWAPPED
119 } swapped_type_t;
120
121 typedef enum {
122 PASS_THROUGH,
123 SCALE_UP,
124 SCALE_DOWN
125 } tstamp_scale_type_t;
126
127 struct pcap_sf {
128 size_t hdrsize;
129 swapped_type_t lengths_swapped;
130 tstamp_scale_type_t scale_type;
131 };
132
133 /*
134 * Check whether this is a pcap savefile and, if it is, extract the
135 * relevant information from the header.
136 */
137 pcap_t *
pcap_check_header(bpf_u_int32 magic,FILE * fp,u_int precision,char * errbuf,int * err)138 pcap_check_header(bpf_u_int32 magic, FILE *fp, u_int precision, char *errbuf,
139 int *err)
140 {
141 struct pcap_file_header hdr;
142 size_t amt_read;
143 pcap_t *p;
144 int swapped = 0;
145 struct pcap_sf *ps;
146
147 /*
148 * Assume no read errors.
149 */
150 *err = 0;
151
152 /*
153 * Check whether the first 4 bytes of the file are the magic
154 * number for a pcap savefile, or for a byte-swapped pcap
155 * savefile.
156 */
157 if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC &&
158 magic != NSEC_TCPDUMP_MAGIC) {
159 magic = SWAPLONG(magic);
160 if (magic != TCPDUMP_MAGIC && magic != KUZNETZOV_TCPDUMP_MAGIC &&
161 magic != NSEC_TCPDUMP_MAGIC)
162 return (NULL); /* nope */
163 swapped = 1;
164 }
165
166 /*
167 * They are. Put the magic number in the header, and read
168 * the rest of the header.
169 */
170 hdr.magic = magic;
171 amt_read = fread(((char *)&hdr) + sizeof hdr.magic, 1,
172 sizeof(hdr) - sizeof(hdr.magic), fp);
173 if (amt_read != sizeof(hdr) - sizeof(hdr.magic)) {
174 if (ferror(fp)) {
175 pcap_fmt_errmsg_for_errno(errbuf, PCAP_ERRBUF_SIZE,
176 errno, "error reading dump file");
177 } else {
178 pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
179 "truncated dump file; tried to read %lu file header bytes, only got %lu",
180 (unsigned long)sizeof(hdr),
181 (unsigned long)amt_read);
182 }
183 *err = 1;
184 return (NULL);
185 }
186
187 /*
188 * If it's a byte-swapped capture file, byte-swap the header.
189 */
190 if (swapped) {
191 hdr.version_major = SWAPSHORT(hdr.version_major);
192 hdr.version_minor = SWAPSHORT(hdr.version_minor);
193 hdr.thiszone = SWAPLONG(hdr.thiszone);
194 hdr.sigfigs = SWAPLONG(hdr.sigfigs);
195 hdr.snaplen = SWAPLONG(hdr.snaplen);
196 hdr.linktype = SWAPLONG(hdr.linktype);
197 }
198
199 if (hdr.version_major < PCAP_VERSION_MAJOR) {
200 pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
201 "archaic pcap savefile format");
202 *err = 1;
203 return (NULL);
204 }
205
206 /*
207 * currently only versions 2.[0-4] are supported with
208 * the exception of 543.0 for DG/UX tcpdump.
209 */
210 if (! ((hdr.version_major == PCAP_VERSION_MAJOR &&
211 hdr.version_minor <= PCAP_VERSION_MINOR) ||
212 (hdr.version_major == 543 &&
213 hdr.version_minor == 0))) {
214 pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
215 "unsupported pcap savefile version %u.%u",
216 hdr.version_major, hdr.version_minor);
217 *err = 1;
218 return NULL;
219 }
220
221 /*
222 * OK, this is a good pcap file.
223 * Allocate a pcap_t for it.
224 */
225 p = pcap_open_offline_common(errbuf, sizeof (struct pcap_sf));
226 if (p == NULL) {
227 /* Allocation failed. */
228 *err = 1;
229 return (NULL);
230 }
231 p->swapped = swapped;
232 p->version_major = hdr.version_major;
233 p->version_minor = hdr.version_minor;
234 p->tzoff = hdr.thiszone;
235 p->snapshot = hdr.snaplen;
236 if (p->snapshot <= 0) {
237 /*
238 * Bogus snapshot length; use the maximum for this
239 * link-layer type as a fallback.
240 *
241 * XXX - the only reason why snapshot is signed is
242 * that pcap_snapshot() returns an int, not an
243 * unsigned int.
244 */
245 p->snapshot = max_snaplen_for_dlt(hdr.linktype);
246 }
247 p->linktype = linktype_to_dlt(LT_LINKTYPE(hdr.linktype));
248 p->linktype_ext = LT_LINKTYPE_EXT(hdr.linktype);
249
250 p->next_packet_op = pcap_next_packet;
251
252 ps = p->priv;
253
254 p->opt.tstamp_precision = precision;
255
256 /*
257 * Will we need to scale the timestamps to match what the
258 * user wants?
259 */
260 switch (precision) {
261
262 case PCAP_TSTAMP_PRECISION_MICRO:
263 if (magic == NSEC_TCPDUMP_MAGIC) {
264 /*
265 * The file has nanoseconds, the user
266 * wants microseconds; scale the
267 * precision down.
268 */
269 ps->scale_type = SCALE_DOWN;
270 } else {
271 /*
272 * The file has microseconds, the
273 * user wants microseconds; nothing to do.
274 */
275 ps->scale_type = PASS_THROUGH;
276 }
277 break;
278
279 case PCAP_TSTAMP_PRECISION_NANO:
280 if (magic == NSEC_TCPDUMP_MAGIC) {
281 /*
282 * The file has nanoseconds, the
283 * user wants nanoseconds; nothing to do.
284 */
285 ps->scale_type = PASS_THROUGH;
286 } else {
287 /*
288 * The file has microoseconds, the user
289 * wants nanoseconds; scale the
290 * precision up.
291 */
292 ps->scale_type = SCALE_UP;
293 }
294 break;
295
296 default:
297 pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE,
298 "unknown time stamp resolution %u", precision);
299 free(p);
300 *err = 1;
301 return (NULL);
302 }
303
304 /*
305 * We interchanged the caplen and len fields at version 2.3,
306 * in order to match the bpf header layout. But unfortunately
307 * some files were written with version 2.3 in their headers
308 * but without the interchanged fields.
309 *
310 * In addition, DG/UX tcpdump writes out files with a version
311 * number of 543.0, and with the caplen and len fields in the
312 * pre-2.3 order.
313 */
314 switch (hdr.version_major) {
315
316 case 2:
317 if (hdr.version_minor < 3)
318 ps->lengths_swapped = SWAPPED;
319 else if (hdr.version_minor == 3)
320 ps->lengths_swapped = MAYBE_SWAPPED;
321 else
322 ps->lengths_swapped = NOT_SWAPPED;
323 break;
324
325 case 543:
326 ps->lengths_swapped = SWAPPED;
327 break;
328
329 default:
330 ps->lengths_swapped = NOT_SWAPPED;
331 break;
332 }
333
334 if (magic == KUZNETZOV_TCPDUMP_MAGIC) {
335 /*
336 * XXX - the patch that's in some versions of libpcap
337 * changes the packet header but not the magic number,
338 * and some other versions with this magic number have
339 * some extra debugging information in the packet header;
340 * we'd have to use some hacks^H^H^H^H^Hheuristics to
341 * detect those variants.
342 *
343 * Ethereal does that, but it does so by trying to read
344 * the first two packets of the file with each of the
345 * record header formats. That currently means it seeks
346 * backwards and retries the reads, which doesn't work
347 * on pipes. We want to be able to read from a pipe, so
348 * that strategy won't work; we'd have to buffer some
349 * data ourselves and read from that buffer in order to
350 * make that work.
351 */
352 ps->hdrsize = sizeof(struct pcap_sf_patched_pkthdr);
353
354 if (p->linktype == DLT_EN10MB) {
355 /*
356 * This capture might have been done in raw mode
357 * or cooked mode.
358 *
359 * If it was done in cooked mode, p->snapshot was
360 * passed to recvfrom() as the buffer size, meaning
361 * that the most packet data that would be copied
362 * would be p->snapshot. However, a faked Ethernet
363 * header would then have been added to it, so the
364 * most data that would be in a packet in the file
365 * would be p->snapshot + 14.
366 *
367 * We can't easily tell whether the capture was done
368 * in raw mode or cooked mode, so we'll assume it was
369 * cooked mode, and add 14 to the snapshot length.
370 * That means that, for a raw capture, the snapshot
371 * length will be misleading if you use it to figure
372 * out why a capture doesn't have all the packet data,
373 * but there's not much we can do to avoid that.
374 */
375 p->snapshot += 14;
376 }
377 } else
378 ps->hdrsize = sizeof(struct pcap_sf_pkthdr);
379
380 /*
381 * Allocate a buffer for the packet data.
382 * Choose the minimum of the file's snapshot length and 2K bytes;
383 * that should be enough for most network packets - we'll grow it
384 * if necessary. That way, we don't allocate a huge chunk of
385 * memory just because there's a huge snapshot length, as the
386 * snapshot length might be larger than the size of the largest
387 * packet.
388 */
389 p->bufsize = p->snapshot;
390 if (p->bufsize > 2048)
391 p->bufsize = 2048;
392 p->buffer = malloc(p->bufsize);
393 if (p->buffer == NULL) {
394 pcap_snprintf(errbuf, PCAP_ERRBUF_SIZE, "out of memory");
395 free(p);
396 *err = 1;
397 return (NULL);
398 }
399
400 p->cleanup_op = sf_cleanup;
401
402 return (p);
403 }
404
405 /*
406 * Grow the packet buffer to the specified size.
407 */
408 static int
grow_buffer(pcap_t * p,u_int bufsize)409 grow_buffer(pcap_t *p, u_int bufsize)
410 {
411 void *bigger_buffer;
412
413 bigger_buffer = realloc(p->buffer, bufsize);
414 if (bigger_buffer == NULL) {
415 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "out of memory");
416 return (0);
417 }
418 p->buffer = bigger_buffer;
419 p->bufsize = bufsize;
420 return (1);
421 }
422
423 /*
424 * Read and return the next packet from the savefile. Return the header
425 * in hdr and a pointer to the contents in data. Return 0 on success, 1
426 * if there were no more packets, and -1 on an error.
427 */
428 static int
pcap_next_packet(pcap_t * p,struct pcap_pkthdr * hdr,u_char ** data)429 pcap_next_packet(pcap_t *p, struct pcap_pkthdr *hdr, u_char **data)
430 {
431 struct pcap_sf *ps = p->priv;
432 struct pcap_sf_patched_pkthdr sf_hdr;
433 FILE *fp = p->rfile;
434 size_t amt_read;
435 bpf_u_int32 t;
436
437 /*
438 * Read the packet header; the structure we use as a buffer
439 * is the longer structure for files generated by the patched
440 * libpcap, but if the file has the magic number for an
441 * unpatched libpcap we only read as many bytes as the regular
442 * header has.
443 */
444 amt_read = fread(&sf_hdr, 1, ps->hdrsize, fp);
445 if (amt_read != ps->hdrsize) {
446 if (ferror(fp)) {
447 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
448 errno, "error reading dump file");
449 return (-1);
450 } else {
451 if (amt_read != 0) {
452 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
453 "truncated dump file; tried to read %lu header bytes, only got %lu",
454 (unsigned long)ps->hdrsize,
455 (unsigned long)amt_read);
456 return (-1);
457 }
458 /* EOF */
459 return (1);
460 }
461 }
462
463 if (p->swapped) {
464 /* these were written in opposite byte order */
465 hdr->caplen = SWAPLONG(sf_hdr.caplen);
466 hdr->len = SWAPLONG(sf_hdr.len);
467 hdr->ts.tv_sec = SWAPLONG(sf_hdr.ts.tv_sec);
468 hdr->ts.tv_usec = SWAPLONG(sf_hdr.ts.tv_usec);
469 } else {
470 hdr->caplen = sf_hdr.caplen;
471 hdr->len = sf_hdr.len;
472 hdr->ts.tv_sec = sf_hdr.ts.tv_sec;
473 hdr->ts.tv_usec = sf_hdr.ts.tv_usec;
474 }
475
476 switch (ps->scale_type) {
477
478 case PASS_THROUGH:
479 /*
480 * Just pass the time stamp through.
481 */
482 break;
483
484 case SCALE_UP:
485 /*
486 * File has microseconds, user wants nanoseconds; convert
487 * it.
488 */
489 hdr->ts.tv_usec = hdr->ts.tv_usec * 1000;
490 break;
491
492 case SCALE_DOWN:
493 /*
494 * File has nanoseconds, user wants microseconds; convert
495 * it.
496 */
497 hdr->ts.tv_usec = hdr->ts.tv_usec / 1000;
498 break;
499 }
500
501 /* Swap the caplen and len fields, if necessary. */
502 switch (ps->lengths_swapped) {
503
504 case NOT_SWAPPED:
505 break;
506
507 case MAYBE_SWAPPED:
508 if (hdr->caplen <= hdr->len) {
509 /*
510 * The captured length is <= the actual length,
511 * so presumably they weren't swapped.
512 */
513 break;
514 }
515 /* FALLTHROUGH */
516
517 case SWAPPED:
518 t = hdr->caplen;
519 hdr->caplen = hdr->len;
520 hdr->len = t;
521 break;
522 }
523
524 /*
525 * Is the packet bigger than we consider sane?
526 */
527 if (hdr->caplen > max_snaplen_for_dlt(p->linktype)) {
528 /*
529 * Yes. This may be a damaged or fuzzed file.
530 *
531 * Is it bigger than the snapshot length?
532 * (We don't treat that as an error if it's not
533 * bigger than the maximum we consider sane; see
534 * below.)
535 */
536 if (hdr->caplen > (bpf_u_int32)p->snapshot) {
537 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
538 "invalid packet capture length %u, bigger than "
539 "snaplen of %d", hdr->caplen, p->snapshot);
540 } else {
541 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
542 "invalid packet capture length %u, bigger than "
543 "maximum of %u", hdr->caplen,
544 max_snaplen_for_dlt(p->linktype));
545 }
546 return (-1);
547 }
548
549 if (hdr->caplen > (bpf_u_int32)p->snapshot) {
550 /*
551 * The packet is bigger than the snapshot length
552 * for this file.
553 *
554 * This can happen due to Solaris 2.3 systems tripping
555 * over the BUFMOD problem and not setting the snapshot
556 * length correctly in the savefile header.
557 *
558 * libpcap 0.4 and later on Solaris 2.3 should set the
559 * snapshot length correctly in the pcap file header,
560 * even though they don't set a snapshot length in bufmod
561 * (the buggy bufmod chops off the *beginning* of the
562 * packet if a snapshot length is specified); they should
563 * also reduce the captured length, as supplied to the
564 * per-packet callback, to the snapshot length if it's
565 * greater than the snapshot length, so the code using
566 * libpcap should see the packet cut off at the snapshot
567 * length, even though the full packet is copied up to
568 * userland.
569 *
570 * However, perhaps some versions of libpcap failed to
571 * set the snapshot length currectly in the file header
572 * or the per-packet header, or perhaps this is a
573 * corrupted safefile or a savefile built/modified by a
574 * fuzz tester, so we check anyway. We grow the buffer
575 * to be big enough for the snapshot length, read up
576 * to the snapshot length, discard the rest of the
577 * packet, and report the snapshot length as the captured
578 * length; we don't want to hand our caller a packet
579 * bigger than the snapshot length, because they might
580 * be assuming they'll never be handed such a packet,
581 * and might copy the packet into a snapshot-length-
582 * sized buffer, assuming it'll fit.
583 */
584 size_t bytes_to_discard;
585 size_t bytes_to_read, bytes_read;
586 char discard_buf[4096];
587
588 if (hdr->caplen > p->bufsize) {
589 /*
590 * Grow the buffer to the snapshot length.
591 */
592 if (!grow_buffer(p, p->snapshot))
593 return (-1);
594 }
595
596 /*
597 * Read the first p->snapshot bytes into the buffer.
598 */
599 amt_read = fread(p->buffer, 1, p->snapshot, fp);
600 if (amt_read != (bpf_u_int32)p->snapshot) {
601 if (ferror(fp)) {
602 pcap_fmt_errmsg_for_errno(p->errbuf,
603 PCAP_ERRBUF_SIZE, errno,
604 "error reading dump file");
605 } else {
606 /*
607 * Yes, this uses hdr->caplen; technically,
608 * it's true, because we would try to read
609 * and discard the rest of those bytes, and
610 * that would fail because we got EOF before
611 * the read finished.
612 */
613 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
614 "truncated dump file; tried to read %u captured bytes, only got %lu",
615 p->snapshot, (unsigned long)amt_read);
616 }
617 return (-1);
618 }
619
620 /*
621 * Now read and discard what's left.
622 */
623 bytes_to_discard = hdr->caplen - p->snapshot;
624 bytes_read = amt_read;
625 while (bytes_to_discard != 0) {
626 bytes_to_read = bytes_to_discard;
627 if (bytes_to_read > sizeof (discard_buf))
628 bytes_to_read = sizeof (discard_buf);
629 amt_read = fread(discard_buf, 1, bytes_to_read, fp);
630 bytes_read += amt_read;
631 if (amt_read != bytes_to_read) {
632 if (ferror(fp)) {
633 pcap_fmt_errmsg_for_errno(p->errbuf,
634 PCAP_ERRBUF_SIZE, errno,
635 "error reading dump file");
636 } else {
637 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
638 "truncated dump file; tried to read %u captured bytes, only got %lu",
639 hdr->caplen, (unsigned long)bytes_read);
640 }
641 return (-1);
642 }
643 bytes_to_discard -= amt_read;
644 }
645
646 /*
647 * Adjust caplen accordingly, so we don't get confused later
648 * as to how many bytes we have to play with.
649 */
650 hdr->caplen = p->snapshot;
651 } else {
652 if (hdr->caplen > p->bufsize) {
653 /*
654 * Grow the buffer to the next power of 2, or
655 * the snaplen, whichever is lower.
656 */
657 u_int new_bufsize;
658
659 new_bufsize = hdr->caplen;
660 /*
661 * http://graphics.stanford.edu/~seander/bithacks.html#RoundUpPowerOf2
662 */
663 new_bufsize--;
664 new_bufsize |= new_bufsize >> 1;
665 new_bufsize |= new_bufsize >> 2;
666 new_bufsize |= new_bufsize >> 4;
667 new_bufsize |= new_bufsize >> 8;
668 new_bufsize |= new_bufsize >> 16;
669 new_bufsize++;
670
671 if (new_bufsize > (u_int)p->snapshot)
672 new_bufsize = p->snapshot;
673
674 if (!grow_buffer(p, new_bufsize))
675 return (-1);
676 }
677
678 /* read the packet itself */
679 amt_read = fread(p->buffer, 1, hdr->caplen, fp);
680 if (amt_read != hdr->caplen) {
681 if (ferror(fp)) {
682 pcap_fmt_errmsg_for_errno(p->errbuf,
683 PCAP_ERRBUF_SIZE, errno,
684 "error reading dump file");
685 } else {
686 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
687 "truncated dump file; tried to read %u captured bytes, only got %lu",
688 hdr->caplen, (unsigned long)amt_read);
689 }
690 return (-1);
691 }
692 }
693 *data = p->buffer;
694
695 if (p->swapped)
696 swap_pseudo_headers(p->linktype, hdr, *data);
697
698 return (0);
699 }
700
701 static int
sf_write_header(pcap_t * p,FILE * fp,int linktype,int thiszone,int snaplen)702 sf_write_header(pcap_t *p, FILE *fp, int linktype, int thiszone, int snaplen)
703 {
704 struct pcap_file_header hdr;
705
706 hdr.magic = p->opt.tstamp_precision == PCAP_TSTAMP_PRECISION_NANO ? NSEC_TCPDUMP_MAGIC : TCPDUMP_MAGIC;
707 hdr.version_major = PCAP_VERSION_MAJOR;
708 hdr.version_minor = PCAP_VERSION_MINOR;
709
710 hdr.thiszone = thiszone;
711 hdr.snaplen = snaplen;
712 hdr.sigfigs = 0;
713 hdr.linktype = linktype;
714
715 if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1)
716 return (-1);
717
718 return (0);
719 }
720
721 /*
722 * Output a packet to the initialized dump file.
723 */
724 void
pcap_dump(u_char * user,const struct pcap_pkthdr * h,const u_char * sp)725 pcap_dump(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
726 {
727 register FILE *f;
728 struct pcap_sf_pkthdr sf_hdr;
729
730 f = (FILE *)user;
731 sf_hdr.ts.tv_sec = h->ts.tv_sec;
732 sf_hdr.ts.tv_usec = h->ts.tv_usec;
733 sf_hdr.caplen = h->caplen;
734 sf_hdr.len = h->len;
735 /* XXX we should check the return status */
736 (void)fwrite(&sf_hdr, sizeof(sf_hdr), 1, f);
737 (void)fwrite(sp, h->caplen, 1, f);
738 }
739
740 static pcap_dumper_t *
pcap_setup_dump(pcap_t * p,int linktype,FILE * f,const char * fname)741 pcap_setup_dump(pcap_t *p, int linktype, FILE *f, const char *fname)
742 {
743
744 #if defined(_WIN32) || defined(MSDOS)
745 /*
746 * If we're writing to the standard output, put it in binary
747 * mode, as savefiles are binary files.
748 *
749 * Otherwise, we turn off buffering.
750 * XXX - why? And why not on the standard output?
751 */
752 if (f == stdout)
753 SET_BINMODE(f);
754 else
755 setvbuf(f, NULL, _IONBF, 0);
756 #endif
757 if (sf_write_header(p, f, linktype, p->tzoff, p->snapshot) == -1) {
758 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
759 errno, "Can't write to %s", fname);
760 if (f != stdout)
761 (void)fclose(f);
762 return (NULL);
763 }
764 return ((pcap_dumper_t *)f);
765 }
766
767 /*
768 * Initialize so that sf_write() will output to the file named 'fname'.
769 */
770 pcap_dumper_t *
pcap_dump_open(pcap_t * p,const char * fname)771 pcap_dump_open(pcap_t *p, const char *fname)
772 {
773 FILE *f;
774 int linktype;
775
776 /*
777 * If this pcap_t hasn't been activated, it doesn't have a
778 * link-layer type, so we can't use it.
779 */
780 if (!p->activated) {
781 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
782 "%s: not-yet-activated pcap_t passed to pcap_dump_open",
783 fname);
784 return (NULL);
785 }
786 linktype = dlt_to_linktype(p->linktype);
787 if (linktype == -1) {
788 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
789 "%s: link-layer type %d isn't supported in savefiles",
790 fname, p->linktype);
791 return (NULL);
792 }
793 linktype |= p->linktype_ext;
794
795 if (fname == NULL) {
796 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
797 "A null pointer was supplied as the file name");
798 return NULL;
799 }
800 if (fname[0] == '-' && fname[1] == '\0') {
801 f = stdout;
802 fname = "standard output";
803 } else {
804 /*
805 * "b" is supported as of C90, so *all* UN*Xes should
806 * support it, even though it does nothing. It's
807 * required on Windows, as the file is a binary file
808 * and must be written in binary mode.
809 */
810 f = fopen(fname, "wb");
811 if (f == NULL) {
812 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
813 errno, "%s", fname);
814 return (NULL);
815 }
816 }
817 return (pcap_setup_dump(p, linktype, f, fname));
818 }
819
820 /*
821 * Initialize so that sf_write() will output to the given stream.
822 */
823 pcap_dumper_t *
pcap_dump_fopen(pcap_t * p,FILE * f)824 pcap_dump_fopen(pcap_t *p, FILE *f)
825 {
826 int linktype;
827
828 linktype = dlt_to_linktype(p->linktype);
829 if (linktype == -1) {
830 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
831 "stream: link-layer type %d isn't supported in savefiles",
832 p->linktype);
833 return (NULL);
834 }
835 linktype |= p->linktype_ext;
836
837 return (pcap_setup_dump(p, linktype, f, "stream"));
838 }
839
840 pcap_dumper_t *
pcap_dump_open_append(pcap_t * p,const char * fname)841 pcap_dump_open_append(pcap_t *p, const char *fname)
842 {
843 FILE *f;
844 int linktype;
845 size_t amt_read;
846 struct pcap_file_header ph;
847
848 linktype = dlt_to_linktype(p->linktype);
849 if (linktype == -1) {
850 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
851 "%s: link-layer type %d isn't supported in savefiles",
852 fname, linktype);
853 return (NULL);
854 }
855
856 if (fname == NULL) {
857 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
858 "A null pointer was supplied as the file name");
859 return NULL;
860 }
861 if (fname[0] == '-' && fname[1] == '\0')
862 return (pcap_setup_dump(p, linktype, stdout, "standard output"));
863
864 /*
865 * "b" is supported as of C90, so *all* UN*Xes should support it,
866 * even though it does nothing. It's required on Windows, as the
867 * file is a binary file and must be read in binary mode.
868 */
869 f = fopen(fname, "rb+");
870 if (f == NULL) {
871 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
872 errno, "%s", fname);
873 return (NULL);
874 }
875
876 /*
877 * Try to read a pcap header.
878 */
879 amt_read = fread(&ph, 1, sizeof (ph), f);
880 if (amt_read != sizeof (ph)) {
881 if (ferror(f)) {
882 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
883 errno, "%s", fname);
884 fclose(f);
885 return (NULL);
886 } else if (feof(f) && amt_read > 0) {
887 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
888 "%s: truncated pcap file header", fname);
889 fclose(f);
890 return (NULL);
891 }
892 }
893
894 #if defined(_WIN32) || defined(MSDOS)
895 /*
896 * We turn off buffering.
897 * XXX - why? And why not on the standard output?
898 */
899 setvbuf(f, NULL, _IONBF, 0);
900 #endif
901
902 /*
903 * If a header is already present and:
904 *
905 * it's not for a pcap file of the appropriate resolution
906 * and the right byte order for this machine;
907 *
908 * the link-layer header types don't match;
909 *
910 * the snapshot lengths don't match;
911 *
912 * return an error.
913 */
914 if (amt_read > 0) {
915 /*
916 * A header is already present.
917 * Do the checks.
918 */
919 switch (ph.magic) {
920
921 case TCPDUMP_MAGIC:
922 if (p->opt.tstamp_precision != PCAP_TSTAMP_PRECISION_MICRO) {
923 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
924 "%s: different time stamp precision, cannot append to file", fname);
925 fclose(f);
926 return (NULL);
927 }
928 break;
929
930 case NSEC_TCPDUMP_MAGIC:
931 if (p->opt.tstamp_precision != PCAP_TSTAMP_PRECISION_NANO) {
932 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
933 "%s: different time stamp precision, cannot append to file", fname);
934 fclose(f);
935 return (NULL);
936 }
937 break;
938
939 case SWAPLONG(TCPDUMP_MAGIC):
940 case SWAPLONG(NSEC_TCPDUMP_MAGIC):
941 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
942 "%s: different byte order, cannot append to file", fname);
943 fclose(f);
944 return (NULL);
945
946 case KUZNETZOV_TCPDUMP_MAGIC:
947 case SWAPLONG(KUZNETZOV_TCPDUMP_MAGIC):
948 case NAVTEL_TCPDUMP_MAGIC:
949 case SWAPLONG(NAVTEL_TCPDUMP_MAGIC):
950 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
951 "%s: not a pcap file to which we can append", fname);
952 fclose(f);
953 return (NULL);
954
955 default:
956 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
957 "%s: not a pcap file", fname);
958 fclose(f);
959 return (NULL);
960 }
961
962 /*
963 * Good version?
964 */
965 if (ph.version_major != PCAP_VERSION_MAJOR ||
966 ph.version_minor != PCAP_VERSION_MINOR) {
967 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
968 "%s: version is %u.%u, cannot append to file", fname,
969 ph.version_major, ph.version_minor);
970 fclose(f);
971 return (NULL);
972 }
973 if ((bpf_u_int32)linktype != ph.linktype) {
974 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
975 "%s: different linktype, cannot append to file", fname);
976 fclose(f);
977 return (NULL);
978 }
979 if ((bpf_u_int32)p->snapshot != ph.snaplen) {
980 pcap_snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
981 "%s: different snaplen, cannot append to file", fname);
982 fclose(f);
983 return (NULL);
984 }
985 } else {
986 /*
987 * A header isn't present; attempt to write it.
988 */
989 if (sf_write_header(p, f, linktype, p->tzoff, p->snapshot) == -1) {
990 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
991 errno, "Can't write to %s", fname);
992 (void)fclose(f);
993 return (NULL);
994 }
995 }
996
997 /*
998 * Start writing at the end of the file.
999 */
1000 if (fseek(f, 0, SEEK_END) == -1) {
1001 pcap_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
1002 errno, "Can't seek to end of %s", fname);
1003 (void)fclose(f);
1004 return (NULL);
1005 }
1006 return ((pcap_dumper_t *)f);
1007 }
1008
1009 FILE *
pcap_dump_file(pcap_dumper_t * p)1010 pcap_dump_file(pcap_dumper_t *p)
1011 {
1012 return ((FILE *)p);
1013 }
1014
1015 long
pcap_dump_ftell(pcap_dumper_t * p)1016 pcap_dump_ftell(pcap_dumper_t *p)
1017 {
1018 return (ftell((FILE *)p));
1019 }
1020
1021 #if defined(HAVE_FSEEKO)
1022 /*
1023 * We have fseeko(), so we have ftello().
1024 * If we have large file support (files larger than 2^31-1 bytes),
1025 * ftello() will give us a current file position with more than 32
1026 * bits.
1027 */
1028 int64_t
pcap_dump_ftell64(pcap_dumper_t * p)1029 pcap_dump_ftell64(pcap_dumper_t *p)
1030 {
1031 return (ftello((FILE *)p));
1032 }
1033 #elif defined(_MSC_VER)
1034 /*
1035 * We have Visual Studio; we support only 2005 and later, so we have
1036 * _ftelli64().
1037 */
1038 int64_t
pcap_dump_ftell64(pcap_dumper_t * p)1039 pcap_dump_ftell64(pcap_dumper_t *p)
1040 {
1041 return (_ftelli64((FILE *)p));
1042 }
1043 #else
1044 /*
1045 * We don't have ftello() or _ftelli64(), so fall back on ftell().
1046 * Either long is 64 bits, in which case ftell() should suffice,
1047 * or this is probably an older 32-bit UN*X without large file
1048 * support, which means you'll probably get errors trying to
1049 * write files > 2^31-1, so it won't matter anyway.
1050 *
1051 * XXX - what about MinGW?
1052 */
1053 int64_t
pcap_dump_ftell64(pcap_dumper_t * p)1054 pcap_dump_ftell64(pcap_dumper_t *p)
1055 {
1056 return (ftell((FILE *)p));
1057 }
1058 #endif
1059
1060 int
pcap_dump_flush(pcap_dumper_t * p)1061 pcap_dump_flush(pcap_dumper_t *p)
1062 {
1063
1064 if (fflush((FILE *)p) == EOF)
1065 return (-1);
1066 else
1067 return (0);
1068 }
1069
1070 void
pcap_dump_close(pcap_dumper_t * p)1071 pcap_dump_close(pcap_dumper_t *p)
1072 {
1073
1074 #ifdef notyet
1075 if (ferror((FILE *)p))
1076 return-an-error;
1077 /* XXX should check return from fclose() too */
1078 #endif
1079 (void)fclose((FILE *)p);
1080 }
1081